(1) Field of the Invention
This invention relates to the manufacture of turbine elements such as airfoils like blades and vanes. More particularly the invention relates to the manufacture of turbine elements via diffusion bonding of multiple components.
(2) Description of the Related Art
The use of diffusion bonding in turbine blade formation is well known. Examples are found in U.S. Pat. Nos. 5,063,662 and 5,711,068, the disclosures of which are incorporated by reference herein as if set forth at length. The ""662 patent discloses a detailed process for forming a twisted hollow blade having internal structure. The process involves the diffusion bonding of two blade halves followed by additional deformation and machining. The ""068 patent discloses a specific situation in which the two blade halves are cut from a single piece and are diffusion bonded with uncut surfaces facing each other.
Accordingly, one aspect of the invention is directed to a method of manufacturing a hollow element. One or more metallic members are each cut into first and second pieces. Each first and second piece has a cut side with a cut side surface and an opposite surface on a side substantially opposite the cut side. The cut sides are machined to form interior features. The uncut sides are machined to form exterior features. Each first piece is assembled with a second piece to form an assembly. The cut sides of the first and second pieces face each other. The assembly is diffusion bonded.
In various implementations, the assembly may involve contacting the cut side surface of each first piece with the cut side surface of the associated second piece. The diffusion bonded assembly may be deformed to twist a portion of the assembly. An exterior of the diffusion bonded assembly may be finish machined. The machining of the cut sides of the first and second pieces may respectively form non-identical first and second interior features. The machining of the uncut sides of the first and second pieces may respectively form non-identical first and second exterior features. The machining of the cut sides of the first and second pieces may respectively form first and second pluralities of ribs. The diffusion bonding may join respective ones of the first plurality of ribs to associated ones of the second plurality of ribs to form a plurality of elongate webs joining the first and second pieces.